CA1328464C - Process for the preparation of phenolic thiocarboxylic acid esters - Google Patents
Process for the preparation of phenolic thiocarboxylic acid estersInfo
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- CA1328464C CA1328464C CA000586412A CA586412A CA1328464C CA 1328464 C CA1328464 C CA 1328464C CA 000586412 A CA000586412 A CA 000586412A CA 586412 A CA586412 A CA 586412A CA 1328464 C CA1328464 C CA 1328464C
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C323/00—Thiols, sulfides, hydropolysulfides or polysulfides substituted by halogen, oxygen or nitrogen atoms, or by sulfur atoms not being part of thio groups
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Abstract
Process for the preparation of Phenolic thiocarboxylic acid esters Abstract of the Disclosure A process for the preparation of compounds of formula I
(I),
(I),
Description
A-16825/+
Process for the preparation of phenolic thiocarboxylic acid esters The present invention relates to a novel single step process for the preparation of thiocarboxylic acid esters by reacting a phenol with formaldehyde and a thiol.
It is known to prepare phenolic thioesters in two steps, either via theMannich base or by reacting appropriate phenols with a thioacid and formaldehyde and subsequently esterifying the acids 80 obtained. Such a process is disclosed, for example, in US patent specification 3 832 328.
however, such two-step processes are complicated.
A single step process for the preparation of phenolic thioethers by reacting the appropriate phenol with formaldehyde and a thiol in the presence of a strong base such as triethylamine or, in particular, an alkali metal hydroxide, as catalyst, is disclosed in US patent specifi-cation 3 553 270. Attempts to prepare phenolic thioesters as well by this method have falled.
A single step process for the preparation of phenolic thioesters by reacting a phenol with formaldehyde and a thioester is disclosed in US
patent specification 4 623 745. In this publication, Cz-C2~dialkylamine~, for example, are cited as catalysts. Specifically, dibutylamine is used as catalyst.
As phenolic thiossters are useful antioxidants, there still exists a need to provide an improved process for their preparation. It has now been found that phenolic thioesters are obtained in high yield and purity in conveniently short reaction times by carrying out the reaction in the presence of mono- or dimethylamine or ~ono- or diethylamine, preferably dimethylamine.
Accordingly, the present inventlon relatet3 to R proce89 for the prepara-tion of compounds of formula I
Rl\
~ _ / z S CnH2n--COO----R3 (I), Rz wherein R~ and R2 are each independently of the other Cl-C4alkyl, R3 i9 C~-C20alkyl or C2-C2Dalkyl which iZ3 interrupted by -0- or -S-, and n ls l or 2, by reacting a phenol of formula II
R
H0--~
/'--' wlth formaldehyde or a compound that release~3 formaldehyde under the reaction conditions, and with a thiol of formula III
CnH2n C00--R3 (III) whereln Rl, Rz, R3 and n are as defined above, in the presence of a base, which process compris3es carrying out the reaction under excess pressure and in the pret3ence of mono- or dimethylamineor mono- or diethylamine as base .
Rl and R2 defined as Cl-C4slky1 may be methyl, ethyl, n-propyl, iso-propyl, n-butyl, ~3ec-butyl or tert-butyl. Preferably R~ i9 methyl and, most preferably, tert-butyl. R2 is preferably tert-butyl.
R3 defined as Cl-C20alkyl i~3, in nddition to the meaning of Rl, for example pentyl, hexyl, n-octyl, oct-3-yl, 2-ethyl-n-hexyl, 1,l,3,3-tetramethylbutyl, nonyl, decyl, dodecyl, tridecyl, hexadecyl, octadecyl or eicosyl. The preferred meaning of R3 i~3 2-ethylhexyl, oct-3-yl or iso-tridecyl (mixture of tridecyl isomers).
Examples of R3 defined as Cz-C20alkyl which i~3 interrupted by -0- or -S-are: methoxymethyl, 2-ethoxyethyl, 2-n-butoxyethyl, 3-n-butoxypropyl, 2-octoxyethyl, 2-hexadecyloxyethyl, 2-ethoxymethyl, butoxymethyl, methoxypropyl, ethoxypropyl, 3-thiaheptyl or 3-thia-5-methylhexyl.
, . ~. ., n is preferably 1.
Preferred compounds obtained by the process of this invention are thosewherein Rl and R2 are each independently of the other methyl or tert-butyl and R3 is C5-C14alkyl, and, most particularly, those wherein Rl and R2 are tert-butyl and n is 1.
Particularly preferred compounds obtained by the process of this inven-tion are those ~herein Rl and Rz are tert-butyl, n i8 1 and R3 is 2-ethylhexyl, oct-3-yl or isotridecyl.
In the process of thls invention, the reactants, namely phenol, form-aldehyde and a thiol, can be used in stoichiometric amounts. On occasion, however, it can be advantageous to use an excess of formaldehyde and/or thiol.
The process of this invention is carried out in the presence of mono- or dimethylamine or mono- or diethylami~e as base. It is preferred to use mono- or timethylamine, most particularly dimethylamine.
The base can be used ln an amount of 1-50 mol%, preferably 10-25 mol%, based on the thiol.
It is particularly expedient to carry out the process of the invention under an excess pressure of 105 to 106 Pa. The reaction temperature is, for example, in the range from 80 to 200C. A preferred temperature range ls from 120 to 150C.
The reaction times can vary, depending on the phenol and the thiol, andare, for example, from 30 minutes ~o 6 hours, preferably from 45 minutes to 4 hours.
The process of the invention can be carried out with or without a solvent. If a solvent is used, about 20 % by weight will suffice, based on the final product. This amount constitutes a substantial reduction compared with the customary amounts of solvent and is an advantage of the process.
Suitable solvents are those in which the reactants are soluble to a certain degree and which are essentially inert under the reaction conditions. Examples of such solvents are hydrocarbons such as toluene, xylene, octane and ~-terpene; ethers such as dioxan, diethyl ether, dimethyl ethers of ethylene glycol, tetrahydrofuran and the like.
Chlorinated hydrocarbons such as carbon tetrachloride, chloroform, trichloroethane, and perchloroethylene can also be conveniently used as solvents. Primary and secondary alcohols of 3 to 6 carbon atoms, for example isopropanol, sec-butyl alcohol, tert-butyl alcohol, tert-amyl alcohol, and hexyl alcohol can also be recommended for successfully carrying out the process of the invention.
It i8 preferred, however, to carry out the process of the invention in the absence of a solvent.
Formaldehyde, or a compound that releases formaldehyde under the reaction conditlons, for example paraformaldehyde or hexamethylenetetramine, is used in the process of the invention. It is preferred to use formaldehyde and, most particularlyl paraformaldehyde.
After the reaction mixture ha~ been cooled, the final product can be obtained, for example, by di~tillation and, if desired, purified.
It is, however, a further advantage of the process of the invention that the final products are obtained in a purity that permits their direct further use for many utilities. If it is nevertheless desired to purify the final products, then the distillation i9 preferably carried out in a flash distillation apparatus, preferably under a pressure of 0.5-5 Pa.
The starting phenols and thiols are known compounds and some are commer-cially available or can be prepared by known methods.
The compounds of formula I prepared by the procPss of this invention are known compounds and can be used as stabilizers for protecting organic material against degradation caused by the action of oxygen, heat, light or energy-rich radiation.
The preferred utility of the compounds is as antioxidants in organic polymers and in elastomers, or in mineral oils or synthetic lubricants as disclosed, for example, in EP-A 0 059 168.
The invention is illustrated in more detail by the following Examples, in which parts and percentages are by weight, unless otherwise stated.
xample 1: Preparation of 2'-eth~lhexyl 3? 5-di-tert-butyl-4-h~droxv-benzylthio~lycolate C~CH3)3 H0-~ CH2-S- CH2-C00 -CH2-CIH-~CHz~CH3 C(CH3~3 HzCH3 An apparatus consisting of a 750 ml reactor (approved up to 3~10 Pa) which i8 equipped with stirrer, thermometer, nitrogen supply and gas inlet pipe, as well as with distillation head with condenser and receiver with vacuum connection, i8 charged in succession with 206.3 g (l.0 mol) of 2,4-di-tert-butylphenol, 36.0 g (1.2 mol) of 100 % paraformaldehyde and 204.0 g (1.0 mol) of 2-ethylhexylthioglycolate. The suspension is blanketed with nitrogen and then, with moderate stirring, evacuated to 2000 Pa and the reactor i~ closed. Then 4.5 g (0.1 mol) of gaseouY
dimethylamlne are passed lnto ths suspenslon through the ga~ lnlet pipe over 10 minutes, whereupon the reaction mixture exotherms slightly and the temperature rises by ca. 5~C and the vacuum in the reaction vessel is ca. 1.2-10~ Pa.
The pale, mobile suspension is heated to 130~C and stirred for 4-5 hours at this temperature, the pressure rising to 2.5-10~ Pa. The suspension becomes a clear, orange-yellow melt which, towards the end of the reaction, becomes highly turbid owing to the water of reaction. The reaction mixture is cooled to 70C and, at this temperature, a mixture of dimethylamine, water and some excess formaldehyde is removed by distilla-tion by applying a vacuum of 2000 Pa, until at 100C and 2000 Pa the distillation is complete.
- 6 - ~ 328464 Yield: 413.5 g (98 % of theory) of the final product with a refractive index nD = 1.5140.
Example 2: The procedure of Example l is repeated, using 146.0 g (2.0 mol) of dimethyl formamide as solvent. The suspension is stirred for 45 minutes at 125C, the pressure rising from ca. 1.2-10~ to 1.5~105 Pa.
, Yield: 435 g (99 % of theory) of the desired final product with a refractive index nD - 1.5120.
Example 3: Preparation of isotridecYl 3,5-di-tert-butyl-4-hydroxybenzy~-thio~lvcolate C~CH3)3 H0--~ C~2- S-CH2- C00--iso-tridecyl*
C~CH3)3 *mixture of tridecanol isomers An apparatus as described in Example 1 is charged at room temperature, in succession, with 164.8 g (0.8 mol) of 2,6-di-tert-butylphenol, 219.6 g (0.8 mol) of l~otridecyl thioglycolate and 26.4 g (0.88 mol) of 100 %
paraformaldehyde.
.
The ~uspension is blanketed with nitrogen and then evacuated to 2000 Pa with moderate stirring, and the reactor is closed. Then 9.3 g (0.206 mol) of gaseous dimethylamine are passed into the suspension through the gas inlet pipe over 10 minutes. The ens~ng reaction i8 markedly exothermic.
The temperature rises by ca. 5-lO~C and the vacuum $n the reactor i9 ca.
2.5-104 Pa.
The pale, mobile suspension is heated to 140C and stirred for 4-5 hours at this temperature, the pressure rising to 2.3-105. The suspension becomes a clear, yellowish-brown melt which, towards the end of the reaction, becomes highly turbid owing to the water of reaction. The reactlon mixture is cooled to 70C and, at this temperature, 10.0 g of fluid cracking catalyst ~C~C~ as absorber are added and, by applying a vacuum of 2000 Pa, a mixture of dimethylamine, water and some excess paraformaldehyde is distilled off until, at 100C, the distillation i9 complete. The melt is the}eafter freed from absorber by clarifying filtration at 100C.
Yield: 375 g (95 % of theory) of the final product with a refractive index nD = 1.5063.
Example 4: The procedure of Example 3 is repeated, using 114.0 g (1.56 mol) of dimethyl formamlde as solvent and 5.7 g (0.126 mol) of dimethylamine. The suspension is stirred at 130-140C for 1.5 hours, the pressure rising to 1.9-105 Pa.
Yield: 367 g (93 Y0 of theory) of the final product with a refractive index nD = 1.5080.
xample 5: Preparation of oct-3-yl 3,5-di-tert-butyl-4-hydroxybenzyl-thio~lycolate C~CH3)3 HO--~ CHz- S--CH2--COO--,CH-CH2CH2CH2CH2CH3 C~CH;)3 CHzCH3 The procedure of Example 3 is repeated, uslng 247.6 g (1.20 mol) of 2,6-di-tert-butylphenol, 244.8 g (1.20 mol) of oct-3-yl thioglycolate, 39.6 g (1.32 mol) of 100 æ paraformaldehyde and 18.0 g (0.40 mol) of dimethylamine. The suspension is stirred for 4 hours at 125C, the pressure rising to 2.3-105 Pa.
Yield: 482 g (95 % of theory) of the final product as a yellow fluid with a refractive index nD = 1.5130.
Example 6: Purification by flash distillation The crude product of each of Examples 1-5 is fed at a rate of 450 g per hour into a flash distillation apparatus (glass 0.04 m2) at a jacket temperature of 160C a condenser temperature of 27C, a wiper speed of 250 rpm and a pressure of 0.5 Pa.
Each distlllation affords a clear, pale yellow to yellow product in a yield of ca. 93 %, based on the amount of crude product.
xample 7: Preparation of 3',4'-dimethvlhex-1'-yl 3,5-di-tert-butyl-4-hvdroxybenzylthioglvcolate C~CH3)3 HO-~ -- CH2- S -CHz- COO-~CH2~-8H- gH- CHzCH3 C~CH3)3 The procedure of Example 1 is repeated, using 247.6 g (1.2 mol) of 2,6-di-tert-butylphenol, 244.8 g (1.2 mol) of isooctyl thioglycolate (mlxture of isomers), 39.6 g (1.32 mol) of paraformaldehyde and 18.0 g (0.4 mol) of dimethylamine. A reaction course identical to that of Example 1 is observed. The pressure rises during the reaction to 2.3-105 Pa.
Yield: 472 g (93 % of theory) of the final product with a refractive index nD~ ~ 1.5145.
This product can be readily further purified by distillation in a thin-film evaporator (head temperature: 240C at 5 mbar), to give the final product in a purity of over 97 %. The density is 1.0043 g/ml at a viscosity (at 40C) of 197-198 mPa-s.
Process for the preparation of phenolic thiocarboxylic acid esters The present invention relates to a novel single step process for the preparation of thiocarboxylic acid esters by reacting a phenol with formaldehyde and a thiol.
It is known to prepare phenolic thioesters in two steps, either via theMannich base or by reacting appropriate phenols with a thioacid and formaldehyde and subsequently esterifying the acids 80 obtained. Such a process is disclosed, for example, in US patent specification 3 832 328.
however, such two-step processes are complicated.
A single step process for the preparation of phenolic thioethers by reacting the appropriate phenol with formaldehyde and a thiol in the presence of a strong base such as triethylamine or, in particular, an alkali metal hydroxide, as catalyst, is disclosed in US patent specifi-cation 3 553 270. Attempts to prepare phenolic thioesters as well by this method have falled.
A single step process for the preparation of phenolic thioesters by reacting a phenol with formaldehyde and a thioester is disclosed in US
patent specification 4 623 745. In this publication, Cz-C2~dialkylamine~, for example, are cited as catalysts. Specifically, dibutylamine is used as catalyst.
As phenolic thiossters are useful antioxidants, there still exists a need to provide an improved process for their preparation. It has now been found that phenolic thioesters are obtained in high yield and purity in conveniently short reaction times by carrying out the reaction in the presence of mono- or dimethylamine or ~ono- or diethylamine, preferably dimethylamine.
Accordingly, the present inventlon relatet3 to R proce89 for the prepara-tion of compounds of formula I
Rl\
~ _ / z S CnH2n--COO----R3 (I), Rz wherein R~ and R2 are each independently of the other Cl-C4alkyl, R3 i9 C~-C20alkyl or C2-C2Dalkyl which iZ3 interrupted by -0- or -S-, and n ls l or 2, by reacting a phenol of formula II
R
H0--~
/'--' wlth formaldehyde or a compound that release~3 formaldehyde under the reaction conditions, and with a thiol of formula III
CnH2n C00--R3 (III) whereln Rl, Rz, R3 and n are as defined above, in the presence of a base, which process compris3es carrying out the reaction under excess pressure and in the pret3ence of mono- or dimethylamineor mono- or diethylamine as base .
Rl and R2 defined as Cl-C4slky1 may be methyl, ethyl, n-propyl, iso-propyl, n-butyl, ~3ec-butyl or tert-butyl. Preferably R~ i9 methyl and, most preferably, tert-butyl. R2 is preferably tert-butyl.
R3 defined as Cl-C20alkyl i~3, in nddition to the meaning of Rl, for example pentyl, hexyl, n-octyl, oct-3-yl, 2-ethyl-n-hexyl, 1,l,3,3-tetramethylbutyl, nonyl, decyl, dodecyl, tridecyl, hexadecyl, octadecyl or eicosyl. The preferred meaning of R3 i~3 2-ethylhexyl, oct-3-yl or iso-tridecyl (mixture of tridecyl isomers).
Examples of R3 defined as Cz-C20alkyl which i~3 interrupted by -0- or -S-are: methoxymethyl, 2-ethoxyethyl, 2-n-butoxyethyl, 3-n-butoxypropyl, 2-octoxyethyl, 2-hexadecyloxyethyl, 2-ethoxymethyl, butoxymethyl, methoxypropyl, ethoxypropyl, 3-thiaheptyl or 3-thia-5-methylhexyl.
, . ~. ., n is preferably 1.
Preferred compounds obtained by the process of this invention are thosewherein Rl and R2 are each independently of the other methyl or tert-butyl and R3 is C5-C14alkyl, and, most particularly, those wherein Rl and R2 are tert-butyl and n is 1.
Particularly preferred compounds obtained by the process of this inven-tion are those ~herein Rl and Rz are tert-butyl, n i8 1 and R3 is 2-ethylhexyl, oct-3-yl or isotridecyl.
In the process of thls invention, the reactants, namely phenol, form-aldehyde and a thiol, can be used in stoichiometric amounts. On occasion, however, it can be advantageous to use an excess of formaldehyde and/or thiol.
The process of this invention is carried out in the presence of mono- or dimethylamine or mono- or diethylami~e as base. It is preferred to use mono- or timethylamine, most particularly dimethylamine.
The base can be used ln an amount of 1-50 mol%, preferably 10-25 mol%, based on the thiol.
It is particularly expedient to carry out the process of the invention under an excess pressure of 105 to 106 Pa. The reaction temperature is, for example, in the range from 80 to 200C. A preferred temperature range ls from 120 to 150C.
The reaction times can vary, depending on the phenol and the thiol, andare, for example, from 30 minutes ~o 6 hours, preferably from 45 minutes to 4 hours.
The process of the invention can be carried out with or without a solvent. If a solvent is used, about 20 % by weight will suffice, based on the final product. This amount constitutes a substantial reduction compared with the customary amounts of solvent and is an advantage of the process.
Suitable solvents are those in which the reactants are soluble to a certain degree and which are essentially inert under the reaction conditions. Examples of such solvents are hydrocarbons such as toluene, xylene, octane and ~-terpene; ethers such as dioxan, diethyl ether, dimethyl ethers of ethylene glycol, tetrahydrofuran and the like.
Chlorinated hydrocarbons such as carbon tetrachloride, chloroform, trichloroethane, and perchloroethylene can also be conveniently used as solvents. Primary and secondary alcohols of 3 to 6 carbon atoms, for example isopropanol, sec-butyl alcohol, tert-butyl alcohol, tert-amyl alcohol, and hexyl alcohol can also be recommended for successfully carrying out the process of the invention.
It i8 preferred, however, to carry out the process of the invention in the absence of a solvent.
Formaldehyde, or a compound that releases formaldehyde under the reaction conditlons, for example paraformaldehyde or hexamethylenetetramine, is used in the process of the invention. It is preferred to use formaldehyde and, most particularlyl paraformaldehyde.
After the reaction mixture ha~ been cooled, the final product can be obtained, for example, by di~tillation and, if desired, purified.
It is, however, a further advantage of the process of the invention that the final products are obtained in a purity that permits their direct further use for many utilities. If it is nevertheless desired to purify the final products, then the distillation i9 preferably carried out in a flash distillation apparatus, preferably under a pressure of 0.5-5 Pa.
The starting phenols and thiols are known compounds and some are commer-cially available or can be prepared by known methods.
The compounds of formula I prepared by the procPss of this invention are known compounds and can be used as stabilizers for protecting organic material against degradation caused by the action of oxygen, heat, light or energy-rich radiation.
The preferred utility of the compounds is as antioxidants in organic polymers and in elastomers, or in mineral oils or synthetic lubricants as disclosed, for example, in EP-A 0 059 168.
The invention is illustrated in more detail by the following Examples, in which parts and percentages are by weight, unless otherwise stated.
xample 1: Preparation of 2'-eth~lhexyl 3? 5-di-tert-butyl-4-h~droxv-benzylthio~lycolate C~CH3)3 H0-~ CH2-S- CH2-C00 -CH2-CIH-~CHz~CH3 C(CH3~3 HzCH3 An apparatus consisting of a 750 ml reactor (approved up to 3~10 Pa) which i8 equipped with stirrer, thermometer, nitrogen supply and gas inlet pipe, as well as with distillation head with condenser and receiver with vacuum connection, i8 charged in succession with 206.3 g (l.0 mol) of 2,4-di-tert-butylphenol, 36.0 g (1.2 mol) of 100 % paraformaldehyde and 204.0 g (1.0 mol) of 2-ethylhexylthioglycolate. The suspension is blanketed with nitrogen and then, with moderate stirring, evacuated to 2000 Pa and the reactor i~ closed. Then 4.5 g (0.1 mol) of gaseouY
dimethylamlne are passed lnto ths suspenslon through the ga~ lnlet pipe over 10 minutes, whereupon the reaction mixture exotherms slightly and the temperature rises by ca. 5~C and the vacuum in the reaction vessel is ca. 1.2-10~ Pa.
The pale, mobile suspension is heated to 130~C and stirred for 4-5 hours at this temperature, the pressure rising to 2.5-10~ Pa. The suspension becomes a clear, orange-yellow melt which, towards the end of the reaction, becomes highly turbid owing to the water of reaction. The reaction mixture is cooled to 70C and, at this temperature, a mixture of dimethylamine, water and some excess formaldehyde is removed by distilla-tion by applying a vacuum of 2000 Pa, until at 100C and 2000 Pa the distillation is complete.
- 6 - ~ 328464 Yield: 413.5 g (98 % of theory) of the final product with a refractive index nD = 1.5140.
Example 2: The procedure of Example l is repeated, using 146.0 g (2.0 mol) of dimethyl formamide as solvent. The suspension is stirred for 45 minutes at 125C, the pressure rising from ca. 1.2-10~ to 1.5~105 Pa.
, Yield: 435 g (99 % of theory) of the desired final product with a refractive index nD - 1.5120.
Example 3: Preparation of isotridecYl 3,5-di-tert-butyl-4-hydroxybenzy~-thio~lvcolate C~CH3)3 H0--~ C~2- S-CH2- C00--iso-tridecyl*
C~CH3)3 *mixture of tridecanol isomers An apparatus as described in Example 1 is charged at room temperature, in succession, with 164.8 g (0.8 mol) of 2,6-di-tert-butylphenol, 219.6 g (0.8 mol) of l~otridecyl thioglycolate and 26.4 g (0.88 mol) of 100 %
paraformaldehyde.
.
The ~uspension is blanketed with nitrogen and then evacuated to 2000 Pa with moderate stirring, and the reactor is closed. Then 9.3 g (0.206 mol) of gaseous dimethylamine are passed into the suspension through the gas inlet pipe over 10 minutes. The ens~ng reaction i8 markedly exothermic.
The temperature rises by ca. 5-lO~C and the vacuum $n the reactor i9 ca.
2.5-104 Pa.
The pale, mobile suspension is heated to 140C and stirred for 4-5 hours at this temperature, the pressure rising to 2.3-105. The suspension becomes a clear, yellowish-brown melt which, towards the end of the reaction, becomes highly turbid owing to the water of reaction. The reactlon mixture is cooled to 70C and, at this temperature, 10.0 g of fluid cracking catalyst ~C~C~ as absorber are added and, by applying a vacuum of 2000 Pa, a mixture of dimethylamine, water and some excess paraformaldehyde is distilled off until, at 100C, the distillation i9 complete. The melt is the}eafter freed from absorber by clarifying filtration at 100C.
Yield: 375 g (95 % of theory) of the final product with a refractive index nD = 1.5063.
Example 4: The procedure of Example 3 is repeated, using 114.0 g (1.56 mol) of dimethyl formamlde as solvent and 5.7 g (0.126 mol) of dimethylamine. The suspension is stirred at 130-140C for 1.5 hours, the pressure rising to 1.9-105 Pa.
Yield: 367 g (93 Y0 of theory) of the final product with a refractive index nD = 1.5080.
xample 5: Preparation of oct-3-yl 3,5-di-tert-butyl-4-hydroxybenzyl-thio~lycolate C~CH3)3 HO--~ CHz- S--CH2--COO--,CH-CH2CH2CH2CH2CH3 C~CH;)3 CHzCH3 The procedure of Example 3 is repeated, uslng 247.6 g (1.20 mol) of 2,6-di-tert-butylphenol, 244.8 g (1.20 mol) of oct-3-yl thioglycolate, 39.6 g (1.32 mol) of 100 æ paraformaldehyde and 18.0 g (0.40 mol) of dimethylamine. The suspension is stirred for 4 hours at 125C, the pressure rising to 2.3-105 Pa.
Yield: 482 g (95 % of theory) of the final product as a yellow fluid with a refractive index nD = 1.5130.
Example 6: Purification by flash distillation The crude product of each of Examples 1-5 is fed at a rate of 450 g per hour into a flash distillation apparatus (glass 0.04 m2) at a jacket temperature of 160C a condenser temperature of 27C, a wiper speed of 250 rpm and a pressure of 0.5 Pa.
Each distlllation affords a clear, pale yellow to yellow product in a yield of ca. 93 %, based on the amount of crude product.
xample 7: Preparation of 3',4'-dimethvlhex-1'-yl 3,5-di-tert-butyl-4-hvdroxybenzylthioglvcolate C~CH3)3 HO-~ -- CH2- S -CHz- COO-~CH2~-8H- gH- CHzCH3 C~CH3)3 The procedure of Example 1 is repeated, using 247.6 g (1.2 mol) of 2,6-di-tert-butylphenol, 244.8 g (1.2 mol) of isooctyl thioglycolate (mlxture of isomers), 39.6 g (1.32 mol) of paraformaldehyde and 18.0 g (0.4 mol) of dimethylamine. A reaction course identical to that of Example 1 is observed. The pressure rises during the reaction to 2.3-105 Pa.
Yield: 472 g (93 % of theory) of the final product with a refractive index nD~ ~ 1.5145.
This product can be readily further purified by distillation in a thin-film evaporator (head temperature: 240C at 5 mbar), to give the final product in a purity of over 97 %. The density is 1.0043 g/ml at a viscosity (at 40C) of 197-198 mPa-s.
Claims (10)
1. A process for the preparation of a compound of formula I
(I), wherein R1 and R2 are each independently of the other C1-C4alkyl, R3 is C1-C20alkyl or C2-C20alkyl which is interrupted by -O- or -S-, and n is 1 or 2, by reacting a phenol of formula II
(II), with formaldehyde or a compound that releases formaldehyde under the reaction conditions, and with a thiol of formula III
HS-CnH2n-COO-R3 (III) wherein R1, R2, R3 and n are as defined above, in the presence of a base, which process comprises carrying out the reaction under excess pressure and in the presence of mono- or dimethylamine or mono- or diethylamine as base.
(I), wherein R1 and R2 are each independently of the other C1-C4alkyl, R3 is C1-C20alkyl or C2-C20alkyl which is interrupted by -O- or -S-, and n is 1 or 2, by reacting a phenol of formula II
(II), with formaldehyde or a compound that releases formaldehyde under the reaction conditions, and with a thiol of formula III
HS-CnH2n-COO-R3 (III) wherein R1, R2, R3 and n are as defined above, in the presence of a base, which process comprises carrying out the reaction under excess pressure and in the presence of mono- or dimethylamine or mono- or diethylamine as base.
2. A process according to claim 1, wherein 1-50 mol% of the base is used, based on the thiol.
3. A process according to claim 1, wherein the reaction is carried out in the absence of a solvent.
4. A process according to claim 1, wherein an excess pressure of 105 to 106 Pa is applied.
5. A process according to claim 1, wherein the reaction temperature is in the range from 120 to 150°C.
6. A process according to claim 1, wherein the crude product of formula I
is purified by flash distillation.
is purified by flash distillation.
7. A process according to claim 1 for the preparation of a compound of formula I, wherein R1 and R2 are each independently of the other methyl or tert-butyl and R3 is C6-C14alkyl.
8. A process according to claim 7 for the preparation of a compound of formula I, wherein R1 and R2 are tert-butyl and n is 1.
9. A process according to claim 8 for the preparation of a compound of formula I, wherein R3 is 2-ethylhexyl, oct-3-yl or isotridecyl.
10. A process according to claim 1, wherein the base is dimethylamine.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH498787 | 1987-12-22 | ||
| CH4987/87-5 | 1987-12-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1328464C true CA1328464C (en) | 1994-04-12 |
Family
ID=4285987
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000586412A Expired - Fee Related CA1328464C (en) | 1987-12-22 | 1988-12-20 | Process for the preparation of phenolic thiocarboxylic acid esters |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US5110978A (en) |
| EP (1) | EP0322360B1 (en) |
| JP (1) | JP2557699B2 (en) |
| BR (1) | BR8806766A (en) |
| CA (1) | CA1328464C (en) |
| DE (1) | DE3866526D1 (en) |
| ES (1) | ES2027798T3 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060183935A1 (en) * | 2005-02-15 | 2006-08-17 | The Lubrizol Corporation | Processing improvements for hindered, ester-substituted phenols |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1288604B (en) * | 1966-08-18 | 1969-02-06 | Advance Prod Gmbh | Stabilization of organic substances against decomposition by oxygen in the heat |
| US3553270A (en) * | 1967-12-22 | 1971-01-05 | Ethyl Corp | Preparation of phenolic thioethers |
| US4623745A (en) * | 1984-07-25 | 1986-11-18 | Ciba-Geigy Corporation | Process for producing phenolic thiocarboxylic esters |
| US4874885A (en) * | 1986-12-24 | 1989-10-17 | Ciba-Geigy Corporation | Process for the preparation of mercaptomethylphenols |
-
1988
- 1988-12-13 EP EP88810859A patent/EP0322360B1/en not_active Expired - Lifetime
- 1988-12-13 ES ES198888810859T patent/ES2027798T3/en not_active Expired - Lifetime
- 1988-12-13 DE DE8888810859T patent/DE3866526D1/en not_active Expired - Lifetime
- 1988-12-20 CA CA000586412A patent/CA1328464C/en not_active Expired - Fee Related
- 1988-12-21 BR BR888806766A patent/BR8806766A/en not_active IP Right Cessation
- 1988-12-22 JP JP63324753A patent/JP2557699B2/en not_active Expired - Lifetime
-
1990
- 1990-12-21 US US07/632,585 patent/US5110978A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0322360B1 (en) | 1991-11-27 |
| BR8806766A (en) | 1989-08-29 |
| US5110978A (en) | 1992-05-05 |
| DE3866526D1 (en) | 1992-01-09 |
| EP0322360A3 (en) | 1989-08-02 |
| ES2027798T3 (en) | 1992-06-16 |
| EP0322360A2 (en) | 1989-06-28 |
| JP2557699B2 (en) | 1996-11-27 |
| JPH02775A (en) | 1990-01-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |